AKA: Black Rock Group; Blue Rock Group
In the case of the Columbia Mine, it appears that whoever wrote the USGS report simply took excerpts from Vanderburg's "Mines of Humboldt and Pershing Counties". From there, the author of that report contradicted themselves on who discovered the mine and when it was discovered. Therefore, I will go straight to Vanderburg as the sole source to clear it up. A man named Verry discovered the area as a whole in 1870. The district was organized in 1875. The Columbia Mine itself was not discovered until 1914 by a man named Clyde Garrett. Those are the details that you will find confusing if you read the USGS Report. Not much was done here until 1936 when the Columbia Mines Company out of Salt Lake City acquired the mine. They mined and shipped 2,000 tons of ore from 1936 through June of 1937. The primary commodity here was gold, along with arsenic, copper and silver as secondaries. The mine employed 12 men during this period of time. The mine consists of a 100- foot vertical shaft and approximately 1,000 of workings. In 1936-1937 when the mine was being worked, it consisted of a "25-horsepower gasoline hoist, a Gardner-Denver portable compressor, an assay office, and camp accommodations for about 14 men." Shipping costs for ore to Winnemucca was $5.00 per ton with six tons being shipped as a load. They were mainly mining the area using the open-stope method. According to the USGS in 1984, the mine had sustained a lot of collapse.
Sources: Mines of Humboldt and Pershing Counties (By: William O. Vanderburg); USGS MRDS Reports- 10045036 Columbia Mine; 10125225 Columbia Mine.